Zero-Knowledge Proof System for Fully Anonymous Attribute Based Group Signatures from Lattices with VLR

Abstract

Signature schemes with Verifier-Local Revocation (VLR) fail to achieve stronger anonymity notion, full-anonymity. In full-anonymity, it is free to corrupt the secret signing keys. Secret signing keys of VLR schemes consist of tokens which can be used to identify the users. Thus VLR schemes restrict corrupting secret signing keys. VLR schemes can achieve full-anonymity by separating tokens from secret signing keys. However, separation of tokens gives space to signers to replace tokens with fake values. Generating signatures with fake tokens can be prevented with a suitable proof system. This paper proposes a new zero-knowledge protocol to support provers to convince verifiers, that attributes used for creating the signature are valid and have naive tokens. Moreover, this paper offers a new Attribute-Based Group Signature (ABGS) scheme, that uses the proposed protocol and achieves full anonymity.